This invention relates generally to method and apparatus for treating fruits and particularly those fruits that are climacteric such as bananas, tomatoes, avocados, melons, pears, honeydews and the like.
More particularly the present invention relates to apparatus and method for treating such fruits that may include ripening these fruits while in typical ventilated boxes closely stacked together on pallets. More specifically the present invention relates to method and apparatus for treating fruits that are climacteric including ripening such fruits that are palletized in mobile trailers without requiring such fruits to be removed from the trailer to be placed in ripening rooms or require other labor intensive air stacking procedures to achieve conditioning of the fruit.
It has always been recognized in the prior art that fruits, particularly those that are climacteric, must have special treating conditions. These conditions control the temperature in order to determine the timing of the ripening process, or maintain these fruits in a controlled temperature environment that allows subsequent ripening of the fruit or marketing of the fruit to the consumer.
In the past, the fruits have been shipped in wooden crates having bowed sides, such as disclosed in U.S. Pat. No. 2,778,206 issued Jan. 22, 1957. These crates were packed close together and were always packed by hand. Attempting to closely pack these crates was an important element of the process in order to achieve the lowest transportation cost by maximizing the average weight per cubic unit of space in the transporter. The problem was always recognized in the art that cooling or, more precisely, precooling of the fruit after loading into the conveyance was important to quickly maintain the desired temperature. If precooling was not achieved, the onset of the initiation of ripening stage would occur and, as is true with the exothermic ripening processes of such fruits, the temperature burden would be beyond the typical trailer or other conveyance to cope with, resulting in a deteriorated or spoiled load of fruit that often would not be useable.
To avoid the prospect of premature ripening, the fruits were maintained at a temperature below the temperature that would cause the onset of the initiation of ripening. Oftentimes this required the crates to be stored in cooling rooms that required the crates to be air stacked, leaving ample space between each of the crates to allow circulation of cooling air, after which the crates were again handled individually to be stacked back into a mobile trailer or other conveyance. It is obvious that this method was extremely expensive because of the requirement of several handlings of the individual crates, and also the requirement for a cooling or refrigerating room of such enormous size and capacity that it would be capable of receiving a substantial number of these air stacked crates.
In more recent years, the fruits have been shipped from their country of origin packed in ventilated, corrugated board boxes in which the fruit is wrapped in plastic liners that have small openings throughout the plastic liner. The typical banana box, for instance, is ten inches high, sixteen inches wide and about thirty-two inches long and is stacked on a pallet eight boxes high.
It is important that the boxes containing the fruit are left on the pallets so as to avoid more handling than necessary. The pallets with the boxes of fruit are carried by forklift trucks, but the boxes must remain stacked in the five boxes per layer arrangement for each of the eight layers throughout any treatment or holding period.
As the palletized fruit leaves the country of origin, the pallets are usually placed in refrigerated containers that can be placed on the ship for transportation and then off loaded onto mobile trailers to be transported to the warehouses at which typically are found the ripening rooms that require manual "air stacking" of the boxes on the pallets with only five boxes per layer. This limit of boxes per layer is required in order to allow space in between individual boxes for air flow when the pallets with the boxes are in the typical ripening or cooling rooms. Withoug such spacing adequate air flow was not possible resulting in uneven ripening and poor quality fruit. Thereafter, ripening of these fruits is to occur in the same boxes.
The ripening process is always supposed to be accomplished in specially designed ripening rooms wherein the fruit is gassed in conventional manner with ethylene and the temperature controlled. Thereafter the boxes on the pallets are returned to the mobile trailer for transportation to distribution centers or retail outlets.
It has long been recognized that it is expensive to retain the intermediate stop at which the palletized fruit in the boxes is to be gassed in a ripening room because it requires off loading from the trailer to the ripening room and then onloading back to the trailer.
The obvious and most economical alternative is to effect the ripening of the fruit in the mobile trailer while being transported to the distributor or retailer, but the typical refrigerated mobile trailer is not adequate to handle the inherent temperature rise caused by the exothermic reaction of ripening should ripening be initiated in the mobile trailer as it is transported from shipside to an ultimate destination. It has been found to the great detriment of the fruit that the great heat output of the ripening process is more than any currently popular trailer is capable of dissipating. The temperature would rise inordinately under such uncontrolled conditions resulting in further escalation of the ripening process and ultimately a deterioration of the fruit.
As well known in the art the concept of initiating the ripening with ethylene is to achieve a uniformity of ripening that will bring the ripening process to a conclusion essentially simultaneously among fruits that may have progressed in the ripening cycle more than their adjacent or neighboring fruits. To achieve this process successfully and bring about uniform ripening, it is essential that the temperature be controlled during the initiation of ripening and the ripening process as well as thereafter. Uniformity of temperature of fruits such as bananas has been the basic requirement to achieve uniformity in ripening. To achieve this uniformity the prior art has always stacked the boxes of fruit with some spaces between the sides of adjacent boxes in order to allow air flow sufficient to carry off the heat from the ripening reaction. These spaces have necessitated that the boxes be stacked five to a single layer on the pallet in order that spaces exist between the adjacent sides. However, it is possible to have every pallet of standard size contain six boxes of identical size as those previously stacked five boxes to a layer and have each of these boxes be in mutual contact at the sides as well as the tops with adjacent boxes. While such an arrangement would obviously be more efficient, there never has been the capability in the art to provide necessary air flow for these closely packed palletized boxes to achieve uniformity of temperature and uniformity of ripening conditions.
To put into proper perspective the amount of heat that is given off by the exothermic reaction, in the past it has been recognized that a large volume of free space in any ripening room is required in order to transport the heat emitted from the ripening of the fruit. Before the palletized fruit such as bananas are admitted to the ripening rooms of the past the air in the ripening room is already at a low temperature so that upon being gassed with ethylene the ripening causes so much heat that unless the pallets were air stacked with substantial spaces between the boxes and the air circulated with large fans that the heat in the ripening room would not be kept under control. The ripening room, however, inasmuch as it is much larger than the volume of the fruit is capable of handling the exothermic ripening reaction. For mobile trailers and other refrigerated transportation means, wherein the boxes are stacked close to the ceiling to preserve and maintain economical transportation costs, the heat generated by the exothermic ripening reaction is simply far beyond the capability of the refrigeration means on the trailer or other conveyance to absorb resulting in damaged fruit that would be unsaleable.
In the U.S. Pat. No. 2,778,206 mentioned above, there is an attempt to meet some of the problems of the prior art particularly in treating fruits that were in crates, as distinguished from the currently used corrugated board boxes, and wherein the crates are packed as close together as possible, giving due allowance to bowed sides that necessarily produce air spaces for channelling air between the boxes. The patent discloses a treating apparatus for boxes of fruit that are packed into mobile trailers and includes a flexible snout that directs air out over the top of the fruit to direct air to the rear portion of the top of the trailer from which the air is shown to be directed downwardly through the spaces occurring between the boxes that are located particularly at the ends of the bowed side slats. It is through these spaces that the volume of chilled air passes through these spaces.
The patent also discloses that a substantial volume of air under pressure is forced out towards the front of the trailer from which it is expected to pass downwardly through these spaces created between the boxes. While uniformity of flow is mentioned, the fact is that uniformity of air flow would not be possible with the boxes placed close up to the front of the trailer. Air flow would not be able to pass down between the boxes in the front and the front of the trailer so as to have access to the fruit in the front portion of these leading boxes. The likely reason that a proper air flow was not as critical for the purposes of the patent was that in the patented apparatus no mention is made of the ripening cycle during which the great exothermic reaction would give off such heat that each of the individual fruits would have to be cooled to prevent damage to any of the individual fruits. Thus, to meet conditions other than ripening, the patented apparatus and method were sufficient.
The patent is believed to be the closest prior art known, but would not meet the requirements of treating the fruit during ripening, as is desired, or at other times successfully, because the air that is passed over the top of the boxes, while controlled to a desired temperature, would not have the proper humidity. The air flow of this patent is not recycled without cooling. Thus, air that passes through the chiller coils would necessarily remove much of this moisture producing low relative humidity air flow that when passed through to the top of the boxes would continually dehydrate the fruit.
The volume of air would also not be sufficient to assure the penetration of the air through the ventilated boxes and through the plastic perforated wrap currently in use unless there was substantially greater volume than is suggested in the patent. The patentee discloses no air space in front of the boxes between the front of the trailer and the first row of boxes to enable air to pass downwardly in front of the boxes in order to be sucked out through the boxes and into contact with the fruit. Additionally, there is no air vane or director or other means to assure that air flow does pass downwardly into the air space so that it can be drawn through the entire contents of the trailer from the front of the first box to the rear of the last box of fruit.